Electrostatic discharge (ESD) may cause damage to semiconductor devices on an integrated circuit during handling of the integrated circuit chip package. Prevention of such damage generally is provided by protection circuits incorporated into the chip of the integrated circuit. In general, such protection circuits include a switch which is capable of conducting relatively large currents during an ESD event. Various devices such as a Silicon Controlled Rectifier (SCR) can be utilized to provide the switching function required to essentially shunt the protected circuitry during an ESD event.
Previous circuits and structures used for ESD protection can withstand high levels of ESD stress. However, recent advances in technology have produced devices which can fail at voltage levels lower than the triggering voltages of prior art protection circuits. Accordingly, a need has developed for improved ESD protection circuits. Similarly, the increased usage of BiCMOS technology in integrated circuitry has created a need for ESD protection in these circuits as well. There is also a need to reduce the complexity and size of the ESD protection circuit.